1. Field of the Invention
The present invention relates to radar chaff, and more particularly to an efficient, low cost method of making radar chaff that completely covers a wide bandwidth. This chaff can be efficiently packed for dispersal by standard dispersal techniques.
2. Description of the Related Art
Radar chaff is generally made from aluminum coated fiberglass which is bundled, cut into lengths, and packed for dispersal. Such chaff absorbs and returns radar most efficiently at frequencies which induce resonant oscillations of electromagnetic waves in the fiber lengths. Because a limited number of different segment lengths are packed into a bundle, the radar response to chaff is maximal at a relatively limited number of frequencies. For example, as shown in FIG. 1, a bundle 10 of aluminum-coated glass fibers 12 may have several smaller bundles 14 of several varying lengths, divided by separators 16, stacked for dispersal.
One possible means for packing a greater variety of lengths of chaff into tubular containers is to use metal rings of varying diameters. Efforts have been made to fabricate metal rings of differing sizes by punching them from metal foil or from thin plastic sheets coated with a metal film, but these attempts have not yielded rings of sufficiently well controlled size to make them useful as chaff. The individual metal rings should preferably have thicknesses near 0.001", and have inner and outer radii differing by about the same amount (i.e., they should have cross sections of about 0.001".times.0.001"). However, there is no reliable method for punching concentric rings of such fine cross sections. Also, when rings of larger cross-section have been made, great difficulty has been experienced in efforts to stack the rings in arrays.